gms | German Medical Science

Introduction: Radio-guided surgery (RGS) is an intraoperative localising technique for the detection of cancer tissue using tumour-specific radionuclides.

The use of RGS has technically advanced and expanded in different kinds of tumour surgery. As of yet the experience with high energy gamma probe in the neuroendocrine tumour is very limited. Previous studies of the intraoperative use of a handheld gamma probe to localize metastases and primary tumours have shown improved assessment of tumour spread and changes in surgical management based on added information gained by radioimmunoguided surgery.The aim of this study was to test the feasibility and advantages of doing RGS using short lived positron emitters ⁶⁸Gallium labelled with synthetic analogues in the intraoperative detection in NET.

Materials and methods: A total of 9 patients ([⁶⁸Ga]-SMS-R-PET/CT imaging was performed preoperatively in all the patients) with ileal (7), CUP (1) and pancreatic (1) neuroendocrine tumours were included. Statistical analyses was performed to find out the correlation between the pathological size of the tumour lesions and the maximum standardised uptake value (SUVmax) on PET/CT as well as the target/non-target ratio (T/NT) of gamma probe counts.

Results: Intraoperativly, overall 72 locations in 9 patients were examined using Gamma-probes. Two operating surgeons noted marked ease in differentiating tumour tissue from scarred areas under gamma probe guidance. 14 lesions (0.4 – 2.5 cm) were surgically removed. Mean tumour size was found to be 1.47 ± 0.6 cm, T/NT was 9.1 ± 6.7, mean SUVmax: 14.3 ± 15.9. There was significant correlation between the T/NT and tumour size (p=0.05) as well as between SUVmax and tumour size (p=0.07).

Conclusion: Handheld gamma probe surgery using 68Ga- somatostatin analogues appears to be feasible and may be an attractive option for detection of small metastases and primaries of neuroendocrine tumours. The lesion detection by the surgeons using gamma probe could eased up as compared PET/CT alone or to naked eye evaluation especially in detection of peritoneal seedings and small lymph node metastases.